pointing linked objects to a different file in 2.8+
Linking to version numbered files is a bad practice and not very maintainable in the long run as you have already found out.

My advice is to never link to myAsset_v002.blend or myAsset_v004.blend, instead when you edit a library file always save "masters files" of all your libraries in addition to the revision ones named myAsset.blend (without version numbers) and link to that one instead. Otherwise you will spend more time managing libraries than getting actual work done.

Addressing the issue at hand you can switch the Outliner to Blend File mode from the dropdown, locate the desired file you which to remap, and from the Right-Click menu choose the Relocate option. Browse to the new substitution file.



You can't, as far as I can tell, quickly select all objects originating from the same blend file, but you can select all objects sharing the same datablock.

In the 3D view you can select all instances on a certain object-data by selecting one of them and from the Shift + L Select Linked menu then picking the relevant entry depending on the library type (if it was linked directly as an object, or a collection instance).



You can take advantage of that and after linking in a new library from a different file, re-link all selected ones using the Ctrl + L Make Links menu, choosing once again the appropriate option depending on the library type.